The present invention relates to a process for the manufacture of super fine woven worsted wool fabric. More particularly, the invention relates to a process by which a polymer filament is combined with single wool yarn, and consequently reaching higher resistance toward abrasion, higher tensile strength and reducing the hairiness of the yarn.
The manufacture of woven wool fabric is a well-known multistep process. Usually worsted weaving yarns are spun into a single yarn structure and then plied, e.g., two single yarns are twisted together in the opposite direction of the spinning twist (regular yarn) or in the same direction of the spinning twist (crepe yarn). Yarns are twisted together (folded yarn) in order to trap into the structure the surface fibers, which subsequently leads to sufficient yarn abrasion resistance, which enables withstanding of the loom action, allowing acceptable weaving efficiency. Another known procedure is to spin two rovings (two separate strands) of wool into siro yarn with spinning twists in xe2x80x9cSxe2x80x9d or xe2x80x9cZxe2x80x9d direction.
The traditional approach for rendering single wool yarn is by yarn sizing. However, it is practically limited to coarser yarn counts. An alternative method is to spin, in the ring spinning frame, water-soluble staple PVA blended intimately with wool to produce a single yarn. However, this method suffers from poor weavability.
U.S. Pat. No. 3,751,897 teaches that the addition of continuous strands of PVA to asbestos produces a reinforced, high tensile strength yarn. In this patent, the core fiber is PVA surrounded by asbestos yarn.
U.S. Pat. No. 5,401,557 teaches the manufacture of water-soluble PVA thread, made from PVA fiber which has a dissolving temperature of at least 70xc2x0 C. This PVA thread is used for reinforcing paper sheets or gummed tapes.
GB 1,075,115 teaches the manufacturing of knitted and woven elastic fabrics, wherein yarns of polyurethane, natural rubber or synthetic rubber having high elasticity, and water-soluble yarns of polyvinyl alcohol are twisted together, so that the elastic yarn is wound around a core of PVA yarn. The twisted yarns are either used in that state, or are shrunk in water, to provide yarns used for knitted or woven fabrics.
The prior art has so far failed to provide means by which super fine single worsted wool yarns, finer than 50 Nm (light count), which can be woven in warp into a very light fabric.
It is a purpose of the present invention to provide a method for overcoming the drawbacks of the known art, to obtain super fine worsted single wool yarn in the warp having improved weavability.
It is another purpose of the invention to provide a process to create a polymer filament shield for a single wool yarn, thus forming a shielded yarn with increased abrasion resistance, increased tensile strength, and decreased yarn hairiness.
It is yet another object of the present invention to provide a method for separating the polymeric shield from the woven article, consequently forming pure wool fabric.
It is a further purpose of the invention to provide a shielding procedure, which is inexpensive and saves production costs.
Other purposes and advantages of the invention will become apparent as the description proceeds.
The invention relates to a process for the manufacturing of a single wool yarn, which can be further used to prepare super fine woven worsted fabric. In one aspect, the invention is directed to the shielding of a wool yarn by the wrapping of a polymeric filament around it, weaving the combined yarn, and subsequently separating the shielded polymer from the wool. As will be appreciated by a skilled person, the wool can be a roving.
According to a preferred embodiment of the invention, the polymer filament is wound or spun together with a core of the wool yarn in a helicoidal fashion.
According to another preferred embodiment of the invention, the winding is by an assembly winding, and the spinning is by a bi-component process.
According to another preferred embodiment of the invention, the polymer is selected from polyhydric alcohol, typically a polyvinyl alcohol or its copolymers. Illustrative and non-limitative examples of the polymers are copolymers of acrylonitrile, acrylic acid, meta-acrylic acid and esters of these acids, and naturally occurring polymers, such as cellulosic derivatives.
According to yet another preferred embodiment of the invention, the separation is effected by dissolving the polymer in a water-based solution. The dissolving process is carried out at temperatures of 75-95xc2x0 C.
The polymer is removed from the wool either prior or after the dyeing step, thereby leaving a fabric made solely of wool.
All the above and other characteristics and advantages of the invention will be further understood through the following illustrative and non-limitative examples.